1. Field of the Invention
Embodiments of the present invention generally relate to semiconductor processing equipment.
2. Description of the Related Art
In some semiconductor processes such as deposition, the substrate may be heated from the back side thereof to provide and maintain a desired temperature of the substrate surface. For example, a radiant light source such as heating lamps may be disposed below the substrate support and utilized to radiate the back side of a susceptor plate having the substrate disposed thereupon.
Unfortunately, with conventional substrate supports, radiant energy from the light source must traverse the components of the substrate support such as a plurality of supporting brackets which support the susceptor plate, or a plurality of lift pins used to raise and lower the substrate, prior to reaching the back side of the susceptor plate. For example, the supporting brackets can cast a thermal shadow on the back side of the susceptor plate, thus creating localized regions of lower temperature on the substrate. In addition, the differing thermal characteristics of the lift pins can result in localized regions of varying temperature on the substrate. Such non-uniform temperature profiles on the substrate can undesirably result in non-uniform thickness of a layer deposited on the substrate in many processes which are temperature dependent.
Thus, there is a need in the art for improved methods and apparatus for providing azimuthal temperature uniformity across a substrate surface.